J.G.
I haven't read the other responses so if this is a repeat, sorry. If it were me, I'd get creative and find a special chair or pillow that he could nap in in his room. Maybe a bean bag chair or one of those that is kid-sized and opens into a bed (sort of foamy and folds up). Maybe when you're visiting someone else you could put sofa cushions on the floor and make a cool chair-bed.
Let him pick it out and really play up how special it is. Sounds like he likes to get out of the crib anyway so you need something new and exciting for him. Good luck!